1. Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Canada
2. Department of Psychiatry, McGill University, Montreal, Canada
3. Department of Psychology, McGill University, Montreal, Canada
4. Centre for Prognosis Research, School of Medicine, Keele University, Staffordshire, UK
5. Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada
6. Respiratory Epidemiology and Clinical Research Unit, McGill University Health Centre, Montreal, Canada
7. Department of Medicine, McGill University, Montreal, Canada